U.S. patent number 11,405,997 [Application Number 17/057,456] was granted by the patent office on 2022-08-02 for lighting control device, lighting control method, and program.
This patent grant is currently assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION. The grantee listed for this patent is NIPPON TELEGRAPH AND TELEPHONE CORPORATION. Invention is credited to Kaoru Hiramatsu, Kunio Kashino, Masaru Tsuchida.
United States Patent |
11,405,997 |
Tsuchida , et al. |
August 2, 2022 |
Lighting control device, lighting control method, and program
Abstract
The chroma of a specific color can be emphasized with respect to
an object without affecting the color of illumination light. An
illumination light generator generates illumination light to be
radiated to the object by adding or subtracting, to or from a
reference illumination light spectrum that is an illumination
spectrum serving as a reference, an element spectrum in accordance
with designated conditions with respect to chroma adjustment from
among a plurality of element spectra that are spectra for being
added or subtracted to or from the reference illumination light
spectrum and for performing chroma emphasis of a specific color
without affecting an illumination light color.
Inventors: |
Tsuchida; Masaru (Tokyo,
JP), Hiramatsu; Kaoru (Tokyo, JP), Kashino;
Kunio (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON TELEGRAPH AND TELEPHONE CORPORATION |
Tokyo |
N/A |
JP |
|
|
Assignee: |
NIPPON TELEGRAPH AND TELEPHONE
CORPORATION (Tokyo, JP)
|
Family
ID: |
1000006468990 |
Appl.
No.: |
17/057,456 |
Filed: |
May 23, 2019 |
PCT
Filed: |
May 23, 2019 |
PCT No.: |
PCT/JP2019/020542 |
371(c)(1),(2),(4) Date: |
November 20, 2020 |
PCT
Pub. No.: |
WO2019/225714 |
PCT
Pub. Date: |
November 28, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20210168914 A1 |
Jun 3, 2021 |
|
Foreign Application Priority Data
|
|
|
|
|
May 24, 2018 [JP] |
|
|
JP2018-099694 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B
47/10 (20200101); H05B 45/20 (20200101); H05B
47/165 (20200101) |
Current International
Class: |
H05B
47/10 (20200101); H05B 47/165 (20200101); H05B
45/20 (20200101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Shigeki Nakauchi (2015) "A Study on Functional LED Lighting Based
on Spectral," Tateishi Science and Technology Foundation Grant
Research Results (No. 24) pp. 30-33. cited by applicant.
|
Primary Examiner: Chang; Daniel D
Claims
The invention claimed is:
1. A computer-implemented method for generating an illumination
light for radiating onto an object, the method comprising:
receiving a predefined condition for chroma adjustment; receiving a
plurality of element spectra, wherein the plurality of element
spectra relate to performing chroma emphasis of a color by
adjusting a reference illumination light spectrum without affecting
an illumination light color; adjusting, based on an element
spectrum of the plurality of element spectra according to the
predefined condition, the reference illumination light spectrum;
generating, using the adjusted reference illumination light
spectrum, the illumination light for radiating to the object; and
outputting the generated illumination light radiating onto the
object.
2. The computer-implemented method of claim 1, the method further
comprising: receiving a plurality of spectral reflection factors in
the object or from a reference color chip; receiving the reference
illumination light spectrum; receiving a plurality of predefined
conditions; and determining the element spectrum based at least on:
the received reference illumination light spectrum, the received
plurality of spectral reflection factors corresponding to the one
or more predefined conditions, and the received plurality of
predefined conditions.
3. The computer-implemented method of claim 2, the method further
comprising: for each of the plurality of predetermined conditions:
determining calculated illumination light spectra based at least
on: the predetermined condition, the reference illumination light
spectrum, and the spectral reflection factors according to the
predefined condition, wherein the calculated illumination light
spectra are adjustable based on chroma of a specific color; and
generating the element spectrum based at least on: the calculated
illumination light spectra satisfying the predetermined condition,
and the reference illumination light spectrum.
4. The computer-implemented method of claim 3, the method further
comprising: determining a composite illumination light spectrum
based at least on: the generated plurality of element spectra, the
received reference illumination light spectrum, and the received
predetermined condition; receiving an illumination light spectrum
measured at the object receiving the illumination light;
determining an error between the composite illumination light
spectrum and the received illumination light spectrum; and
updating, based on the determined error, a spectrum of the
generated illumination light.
5. The computer-implemented method of claim 4, the method further
comprising: when the determined error is less than a predetermined
threshold value, updating, based on the received illumination
spectrum measurement, the reference illumination light
spectrum.
6. The computer-implemented method of claim 5, wherein the received
predetermined condition relates to emphasizing one color of a set
of colors without changing colors of illumination light, the set of
colors including white, blue, green, and red.
7. The computer-implemented method of claim 5, wherein the
plurality of element spectra include: a first element spectrum
emphasizing only blue, a second element spectrum emphasizing only
green, and a third element spectrum emphasizing only red.
8. A system for generating an illumination light for radiating onto
an object, the system comprises: a processor; and a memory storing
computer-executable instructions that when executed by the
processor cause the system to: receive a predefined condition for
chroma adjustment; receive a plurality of element spectra, wherein
the plurality of element spectra relate to performing chroma
emphasis of a color by adjusting a reference illumination light
spectrum without affecting an illumination light color; adjust,
based on an element spectrum of the plurality of element spectra
according to the predefined condition, the reference illumination
light spectrum; generate, using the adjusted reference illumination
light spectrum, the illumination light for radiating to the object;
and output the generated illumination light radiating onto the
object.
9. The system of claim 8, the computer-executable instructions when
executed further causing the system to: receive a plurality of
spectral reflection factors in the object or from a reference color
chip; receive the reference illumination light spectrum; receive a
plurality of predefined conditions; and determine the element
spectrum based at least on: the received reference illumination
light spectrum, the received plurality of spectral reflection
factors corresponding to the one or more predefined conditions, and
the received plurality of predefined conditions.
10. The system of claim 9, the computer-executable instructions
when executed further causing the system to: for each of the
plurality of predetermined conditions: determine calculated
illumination light spectra based at least on: the predetermined
condition, the reference illumination light spectrum, and the
spectral reflection factors according to the predefined condition,
wherein the calculated illumination light spectra are adjustable
based on chroma of a specific color; and generate the element
spectrum based at least on: the calculated illumination light
spectra satisfying the predetermined condition, and the reference
illumination light spectrum.
11. The system of claim 10, the computer-executable instructions
when executed further causing the system to: determine a composite
illumination light spectrum based at least on: the generated
plurality of element spectra, the received reference illumination
light spectrum, and the received predetermined condition; receive
an illumination light spectrum measured at the object receiving the
illumination light; determine an error between the composite
illumination light spectrum and the received illumination light
spectrum; and update, based on the determined error, a spectrum of
the generated illumination light.
12. The system of claim 11, the computer-executable instructions
when executed further causing the system to: when the determined
error is less than a predetermined threshold value, update, based
on the received illumination spectrum measurement, the reference
illumination light spectrum.
13. The system of claim 12, wherein the received predetermined
condition relates to emphasizing one color of a set of colors
without changing colors of illumination light, the set of colors
including white, blue, green, and red.
14. The system of claim 13, wherein the plurality of element
spectra include: a first element spectrum emphasizing only blue, a
second element spectrum emphasizing only green, and a third element
spectrum emphasizing only red.
15. A computer-readable non-transitory recording medium storing
computer-executable instructions that when executed by a processor
cause a computer system to: receive a predefined condition for
chroma adjustment; receive a plurality of element spectra, wherein
the plurality of element spectra relate to performing chroma
emphasis of a color by adjusting a reference illumination light
spectrum without affecting an illumination light color; adjust,
based on an element spectrum of the plurality of element spectra
according to the predefined condition, the reference illumination
light spectrum; generate, using the adjusted reference illumination
light spectrum, the illumination light for radiating to the object;
and output the generated illumination light radiating onto the
object.
16. The computer-readable non-transitory recording medium of claim
15, the computer-executable instructions when executed further
causing the system to: receive a plurality of spectral reflection
factors in the object or from a reference color chip; receive the
reference illumination light spectrum; receive a plurality of
predefined conditions; and determine the element spectrum based at
least on: the received reference illumination light spectrum, the
received plurality of spectral reflection factors corresponding to
the one or more predefined conditions, and the received plurality
of predefined conditions.
17. The computer-readable non-transitory recording medium of claim
16, the computer-executable instructions when executed further
causing the system to: for each of the plurality of predetermined
conditions: determine calculated illumination light spectra based
at least on: the predetermined condition, the reference
illumination light spectrum, and the spectral reflection factors
according to the predefined condition, wherein the calculated
illumination light spectra are adjustable based on chroma of a
specific color; and generate the element spectrum based at least
on: the calculated illumination light spectra satisfying the
predetermined condition, and the reference illumination light
spectrum.
18. The computer-readable non-transitory recording medium of claim
17, the computer-executable instructions when executed further
causing the system to: determine a composite illumination light
spectrum based at least on: the generated plurality of element
spectra, the received reference illumination light spectrum, and
the received predetermined condition; receive an illumination light
spectrum measured at the object receiving the illumination light;
determine an error between the composite illumination light
spectrum and the received illumination light spectrum; and update,
based on the determined error, a spectrum of the generated
illumination light.
19. The computer-readable non-transitory recording medium of claim
18, wherein the received predetermined condition relates to
emphasizing one color of a set of colors without changing colors of
illumination light, the set of colors including white, blue, green,
and red.
20. The computer-readable non-transitory recording medium of claim
19, wherein the plurality of element spectra include: a first
element spectrum emphasizing only blue, a second element spectrum
emphasizing only green, and a third element spectrum emphasizing
only red.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a U.S. 371 Application of International Patent
Application No. PCT/JP2019/020542, filed on 23 May 2019, which
application claims priority to and the benefit of JP Application
No. 2018-099694, filed on 24 May 2018, the disclosures of which are
hereby incorporated herein by reference in their entireties.
TECHNICAL FIELD
The present invention relates to an illumination control apparatus,
an illumination control method, and a program, and particularly, to
an illumination control apparatus, an illumination control method,
and a program for emphasizing the chroma of an object.
BACKGROUND ART
Conventionally, a technology of designing a spectrum of
illumination light most suitable for an object and implementing
generation and control of the illumination light using multi-color
LED light for the purpose of emphasis of the chroma of an entire
image, emphasis of the chroma of mixed foreign substances,
improvement of discrimination of blood vessels under the skin and a
pearl interference color, and the like is known (NPL 1).
CITATION LIST
Non Patent Literature
[NPL 1] Shigeki Nakauchi, "Bunkou Spekutoru Syushoku ni Motozuku
Kinousei LED Syoumei ni Kansuru Kenkyu" (Research on functional
LEDs illuminant based on spectral modification), Tateisi Science
and Technology Foundation, composition research results (Vol. 24),
2015, pp. 30-33
SUMMARY OF THE INVENTION
Technical Problem
However, in the technology of Non-Patent Literature 1, even when
the chroma of only an arbitrary specific color is attempted to be
emphasized, other colors are also affected by chroma emphasis of
the specific color. For example, even when illumination light for
performing chroma emphasis for red is radiated to an object, a
white part of the object is tinged with red. Accordingly, there
were problems that it was impossible to perform chroma emphasis of
only an arbitrary specific color and adjustment of a degree of
chroma emphasis.
In addition, there was a problem that it was extremely difficult to
perform interactive operation because a large amount of
calculations needed to be performed in advance to carry out chroma
emphasis. Furthermore, a large amount of calculation is necessary
for fine adjustment of color appearance.
Moreover, there was a problem that, when the chroma of a certain
color was continuously changed, continuous change of a calculated
illumination light spectrum was not guaranteed and appearance of
the color also became discontinuous due to discontinuous change of
the illumination light spectrum.
An object of the present invention devised in view of the
aforementioned circumstances is to provide an illumination control
apparatus, an illumination control method, and a program which can
emphasize the chroma of a specific color with respect to an object
without affecting the color of illumination light.
Means for Solving the Problem
An illumination control apparatus according to the present
invention is an illumination control apparatus for generating
illumination light to be radiated to an object, including an
illumination light generator which generates illumination light to
be radiated to the object by adding or subtracting, to or from a
reference illumination light spectrum that is an illumination
spectrum serving as a reference, an element spectrum in accordance
with designated conditions with respect to chroma adjustment from
among a plurality of element spectra that are spectra for being
added or subtracted to or from the reference illumination light
spectrum and for performing chroma emphasis of a specific color
without affecting an illumination light color.
An illumination control method according to the present invention
is an illumination control method for generating illumination light
to be radiated to an object, including, by an illumination light
generator, generating illumination light to be radiated to the
object by adding or subtracting, to or from a reference
illumination light spectrum that is an illumination spectrum
serving as a reference, an element spectrum in accordance with
designated conditions with respect to chroma adjustment from among
a plurality of element spectra that are spectra for being added or
subtracted to or from the reference illumination light spectrum and
for performing chroma emphasis of a specific color without
affecting an illumination light color.
According to the illumination control apparatus and the
illumination control method according to the present invention, the
illumination light generator generates illumination light to be
radiated to an object by adding or subtracting, to or from a
reference illumination light spectrum that is an illumination
spectrum serving as a reference, an element spectrum in accordance
with designated conditions with respect to chroma adjustment from
among a plurality of element spectra that are spectra for being
added or subtracted to or from the reference illumination light
spectrum and for performing chroma emphasis of a specific color
without affecting an illumination light color.
In this manner, the illumination light to be radiated to the object
is generated by adding or subtracting, to or from a reference
illumination light spectrum that is an illumination spectrum
serving as a reference, an element spectrum in accordance with
designated conditions with respect to chroma adjustment from among
a plurality of element spectra that are spectra for being added or
subtracted to or from the reference illumination light spectrum and
for performing chroma emphasis of a specific color without
affecting an illumination light color, and thus it is possible to
emphasize the chroma of a specific color with respect to the object
without affecting the color of the illumination light.
Further, the illumination control apparatus according to the
present invention may further include: a spectral reflection factor
acquisition unit which acquires a plurality of spectral reflection
factors in the object or a color chip serving as a reference; a
reference illumination light spectrum acquisition unit which
acquires the reference illumination light spectrum; a designated
condition acquisition unit which acquires a plurality of designated
conditions; and an element spectrum calculator which calculates the
element spectrum that satisfies the designated conditions on the
basis of the reference illumination light spectrum and the spectral
reflection factors corresponding to the designated conditions with
respect to the plurality of designated conditions.
Further, the element spectrum calculator of the illumination
control apparatus according to the present invention may further
include: an illumination light spectrum calculator which calculates
calculated illumination light spectra that are illumination light
spectra and satisfy the designated conditions on the basis of the
reference illumination light spectrum and the spectral reflection
factors corresponding to the designated conditions with respect to
the plurality of designated conditions; and an illumination light
spectrum analyzer which generates the element spectrum that
satisfies the designated conditions on the basis of the calculated
illumination light spectrum that satisfies the designated
conditions and the reference illumination light spectrum with
respect to the plurality of designated conditions.
Further, the illumination control apparatus according to the
present invention may further include: a composite illumination
light spectrum calculator which calculates a composite illumination
light spectrum that is an illumination light spectrum that
satisfies input designated conditions on the basis of the plurality
of element spectra generated by the element spectrum calculator,
the input reference illumination light spectrum, and the input
designated conditions; and a feedback processor which transmits an
error between the composite illumination light spectrum and a
measurement result of a spectrum of the illumination light radiated
to the object to the illumination light generator when the error is
equal to or greater than a predetermined reference value, wherein
the illumination light generator may correct generated illumination
light on the basis of the error.
Further, the feedback processor of the illumination control
apparatus according to the present invention may update the
reference illumination light spectrum to the measurement result of
the spectrum of the illumination light radiated to the object when
the error is less than the predetermined reference value.
The illumination control apparatus according to the present
invention may further include a weighting processor which selects
at least one element spectrum for satisfying input designated
conditions from the plurality of element spectra and determines a
weight for each of the at least one selected element spectrum,
wherein the illumination light generator may generate illumination
light to be radiated to the object by weighting each of the at
least one selected element spectrum and adding or subtracting the
weighted element spectrum to or from the reference illumination
light spectrum.
A program according to the present invention is a program causing a
computer to serve as each component of the illumination control
apparatus.
Effects of the Invention
According to the illumination control apparatus, illumination
control method, and program of the present invention, it is
possible to emphasize the chroma of a specific color with respect
to an object without affecting the color of illumination light.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram showing a configuration of an
illumination control apparatus according to an embodiment of the
present invention.
FIG. 2 is a block diagram showing a configuration of an element
spectrum generator of the illumination control apparatus according
to an embodiment of the present invention.
FIG. 3 is a diagram showing an example of LED spectral radiance of
each color of an LED device using the illumination control
apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram showing an example of a spectral reflection
factor according to an embodiment of the present invention.
FIG. 5 is a diagram showing an example of a reference illumination
light spectrum according to an embodiment of the present
invention.
FIG. 6 is a diagram showing an example of calculated illumination
light spectra that maximize the chromas of blue, green and red
according to an embodiment of the present invention.
FIG. 7 is a diagram showing an example of element spectra
calculated for blue, green and red according to an embodiment of
the present invention.
FIG. 8 is a diagram showing an example of color distributions on a
CIE-u'v' chromaticity diagram when chroma emphasis processing has
been performed on blue, green and red according to an embodiment of
the present invention.
FIG. 9 is a flowchart showing an element spectrum generation
processing routine of the illumination control apparatus according
to an embodiment of the present invention.
FIG. 10 is a flowchart showing an illumination control processing
routine of the illumination control apparatus according to an
embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
Hereinafter, an embodiment of the present invention will be
described with reference to the drawings.
<Principle of Illumination Control Apparatus According to
Embodiment of the Present Invention>
First, the principle of an illumination control apparatus according
to an embodiment of the present invention will be described.
In the present embodiment, an element spectrum e.sub.i for
performing chroma emphasis of only a specific color i is calculated
and illumination control is performed in an illumination control
apparatus which performs illumination control for emphasizing
colors of a drawing and the like.
Metamerism in which "an appearing color does not change even when
an illumination light spectrum is changed" can be formulated as the
following formula (1).
.times..times. ##EQU00001## .times..times..times..times.
.times..times..times..times..times..times. ##EQU00001.2##
Here, "360" and "780" in the above formula represent wavelengths in
the wavelength region of visible light, w=[w.sub.360, . . .
w.sub.780].sup.T and x.sub.i=[x.sub.i,360, . . . x.sub.i,780].sup.T
represent components in 360 nm to 780 nm.
In addition, i is an index indicating a specific color that is a
target of which chroma is intended to be changed (e.g., red, green,
blue, or the like) and j is an index indicating a color for which
metamerism is established (e.g., white that is an illumination
light color, or the like; a situation in which the appearance of
white does not change is called metameric white).
Furthermore, X,Y,Z is a color-matching function (a function having
wavelengths as parameters; colors having the same tristimulus
values obtained by the color-matching function are seen by the
human eye as the same color), [r.sub.j,360, . . .
r.sub.j,780].sup.T represents a plurality of spectral reflection
factors r.sub.j with respect to a color represented by the index j,
w is a reference illumination light spectrum (spectral radiance
distribution, spectrum) that is an illumination light spectrum
serving as a reference of illumination light, and X.sub.i is an
illumination light spectrum for changing the chroma of only a
specific color represented by the index i (hereinafter, calculated
illumination light spectrum).
Here, the chroma of only a specific color represented by the index
i can be emphasized by discovering a calculated illumination light
spectrum X.sub.i that maximizes the value of
|L(CR.sub.iw)-L(CR.sub.ix.sub.i)| through a simulation or the like.
Here, "emphasis" includes decreasing the chroma of only a specific
color as well as increasing the same.
In addition, L(.) is an operator for calculating a CIE-La*b* value.
Further, a method of obtaining the calculated illumination light
spectrum x.sub.i is not limited to the aforementioned method.
Here, the element spectrum e.sub.i of a specific color represented
by the index i is defined as represented by the following formula
(2). [Formula 2] e.sub.i=w-x.sub.i (2)
Here, elements of the element spectrum e.sub.i may include an
element having a negative value.
When the element spectrum e.sub.i is used, the following formula
(3) is defined. [Formula 3] {circumflex over
(x)}.sub.i=w+k.sub.ie.sub.i (3)
Here, k.sub.i is a variable for controlling a chroma. k.sub.i may
be a negative value within a range in which the value of the
illumination light spectrum is not negative. That is, when k.sub.i
is a negative value, the chroma of only a specific color
represented by the index i can be decreased.
Meanwhile, it is possible to confirm from the following formula (4)
that the illumination light spectrum x.sub.i satisfies metamerism
with respect to a color represented by the index j.
.times..times. ##EQU00002##
.function..times..times..function..times..times. ##EQU00002.2##
That is, it is ascertained that the illumination light spectrum
X.sub.i satisfies metamerism with respect to a color represented by
the index j in the formula (4) from the fact that the metamerism
with respect to the color represented by the index j is defined by
the formula (1).
It is possible to emphasize the chromas of various colors with
respect to an object without affecting a color represented by the
index j by using the aforementioned element spectrum e.sub.i.
That is, it is possible to adjust a color to be emphasized and a
degree of emphasis by simply adding/subtracting the element
spectrum e.sub.i to/from the reference illumination light spectrum
w. As a degree of emphasis, any coefficient may be applied to the
element spectrum.
A target color for which the chroma will be adjusted and a color
that is an object of metamerism are not limited to white, blue,
green, red, and the like and may be "bluish green," "yellow,"
"flesh tone," "orange," and the like. When a picture or the like is
an object or a subject is in front of a wall or the like,
background colors that significantly affect appearance (e.g., the
color of a part occupying a large area of the picture, the color of
paper or a canvas, the color of the wall, and the like) may be an
object of metamerism.
<Configuration of Illumination Control Apparatus According to
Embodiment of the Present Invention>
A configuration of the illumination control apparatus 10 according
to an embodiment of the present invention will be described with
reference to FIG. 1. FIG. 1 is a block diagram showing a
configuration of the illumination control apparatus 10 according to
an embodiment of the present invention.
The illumination control apparatus 10 is configured as a computer
including a CPU, a RAM, and a ROM storing a program for executing
an element spectrum generation processing routine and an
illumination control processing routine which will be described
later and functionally configured as follows.
As shown in FIG. 1, the illumination control apparatus 10 according
to the present embodiment is an illumination control apparatus for
generating illumination light to be radiated to an object,
including an element spectrum generator 100, a designated condition
input unit 200, a reference illumination light spectrum input unit
400, a weighting processor 300, a composite illumination light
spectrum calculator 500, an illumination light generator 600, an
output unit 700, and a feedback processor 800.
The element spectrum generator 100 generates element spectra that
are spectra for performing chroma emphasis of a specific color
without affecting an illumination light color in order to perform
addition or subtraction for a reference illumination light spectrum
that is an illumination spectrum serving as a reference.
Specifically, the element spectrum generator 100 includes a
spectral reflection factor acquisition unit 110, an element
spectrum calculator 120, a characteristic information acquisition
unit 130, a reference illumination light spectrum acquisition unit
140, and a designated condition acquisition unit 150 as shown in
FIG. 2.
The characteristic information acquisition unit 130 acquires
statistical information about a target region, a sensitivity
characteristic of an imaging device such as a camera, an
illumination light spectrum during imaging, and a spectral
reflection factor of an object.
Specifically, the characteristic information acquisition unit 130
stores statistical information about a target region for each
color, a sensitivity characteristic of an imaging device, an
illumination light spectrum during imaging, and a spectral
reflection factor of an object or a color chip (hereinafter
collectively referred to as characteristic information) in advance
or receives the characteristic information input by a person.
Then, the characteristic information acquisition unit 130 transmits
the characteristic information to a spectral reflection factor
calculator 112.
The reference illumination light spectrum acquisition unit 140
acquires the reference illumination light spectrum that is an
illumination spectrum serving as a reference using the illumination
control apparatus 10. The reference illumination light spectrum is
a spectrum of illumination light of an environment in which an
object is observed, which has been obtained in advance and is, for
example, solar light, fluorescent light, incandescent light, LED
light, or a combination thereof.
Then, the reference illumination light spectrum acquisition unit
140 transmits the reference illumination light spectrum to an
illumination light spectrum calculator 121.
The designated condition acquisition unit 150 acquires a plurality
of designated conditions with respect to chroma adjustment.
Specifically, the designated condition acquisition unit 150
acquires M assumed designated conditions with respect to designated
conditions on chroma adjustment such as "how to change the
appearance of the color of an object". For example, "the chroma of
blue is maximized without changing the appearance and brightness of
white in a color chart" may be set as a designated condition.
The M designated conditions may be prepared by a person or set as
all designated conditions that can be received by the illumination
control apparatus 10.
In addition, the designated condition acquisition unit 150
transmits the acquired M designated conditions to the illumination
light spectrum calculator 121.
The spectral reflection factor acquisition unit 110 acquires a
plurality of spectral reflection factors in a color chip that is an
object or a reference.
Specifically, the spectral reflection factor acquisition unit 110
includes an imaging unit 111, the spectral reflection factor
calculator 112, and a spectral reflection factor storage 113.
The imaging unit 111 images an image of an object that is a subject
of an observation target, or a color chip such as a color chart
used as a reference with a predetermined number (X) of color
channels (bands) using an imaging device (not shown). Here, since
the number of color channels of an RGB camera that is a general
imaging device is three, the predetermined number is three or more
(X.gtoreq.3).
In addition, the imaging unit 111 may acquire spectral radiance
(spectrum) through spot measurement (measurement at spots) for the
object or the color chip using a spectral radiance meter
(spectrometer or the like) instead of the imaging device.
Then, the imaging unit 111 transmits image data or spectra of the X
color channels to the spectral reflection factor calculator
112.
The spectral reflection factor calculator 112 calculates a
plurality of spectral reflection factors on the basis of the image
data of the X color channels acquired by the imaging unit 111 and
the statistical information about the target region for each color,
the sensitivity characteristic of the imaging device, an
illumination light spectrum during imaging, and a spectral
reflection factor of the object or the color chip, which were
obtained by the characteristic information acquisition unit
130.
As a calculation method, for example, a method of calculating
spectral reflection factors of L colors by obtaining a Wiener
estimation matrix from the statistical information about the
sensitivity characteristic of the imaging device, the illumination
light spectrum during imaging, and the spectral reflection factor
of the object or the color chip for each color and multiplying the
Wiener estimation matrix by pixel values of the X color channels in
a target region of the corresponding color (Wiener estimation
method) may be used.
Meanwhile, a spectral reflection factor calculation method is not
limited to the Wiener estimation method and other existing
techniques may be used.
Then, the spectral reflection factor calculator 112 transmits the
calculated spectral reflection factors of the L colors to the
spectral reflection factor storage 113 as L spectral reflection
factors.
The spectral reflection factor storage 113 stores the L spectral
reflection factors calculated by the spectral reflection factor
calculator 112.
The spectral reflection factor storage 113 may record the L
spectral reflection factors in external storage media.
In addition, the spectral reflection factor storage 113 may store L
spectral reflection factors in an existing spectral reflection
factor database. Further, the spectral reflection factor storage
113 may be configured to store L spectral reflection factors
prepared in advance.
The element spectrum calculator 120 calculates element spectra that
satisfy the plurality of designated conditions on the basis of the
reference illumination light spectrum and spectral reflection
factors corresponding to the designated conditions with respect to
the plurality of designated conditions.
Specifically, the element spectrum calculator 120 includes the
illumination light spectrum calculator 121, an illumination light
spectrum analyzer 122, and an element spectrum storage 123.
The illumination light spectrum calculator 121 calculates
calculated illumination light spectra that are illumination light
spectra satisfying the plurality of designated conditions on the
basis of the reference illumination light spectrum and the spectral
reflection factors corresponding to the designated conditions with
respect to the plurality of designated conditions.
Specifically, first, the illumination light spectrum calculator 121
acquires the L spectral reflection factors stored in the spectral
reflection factor storage 113, the reference illumination light
spectrum acquired by the reference illumination light spectrum
acquisition unit 140, and the M designated conditions acquired by
the designated condition acquisition unit 150.
Next, with respect to the M designated conditions, the illumination
light spectrum calculator 121 calculates calculated illumination
light spectra that are illumination light spectra satisfying the M
designated conditions on the basis of the reference illumination
light spectrum and spectral reflection factors corresponding to the
designated conditions from among the L spectral reflection
factors.
For example, when a designated condition is "only red is emphasized
and illumination light colors are not changed" and the illumination
light colors are white, blue and green, the index i is {red} and
the index j is {white, blue, green}. Accordingly, a calculated
illumination light spectrum x.sub.red with respect to red can be
represented by the following formula (5). [Formula 5]
x.sub.red={tilde over (x)}, (5) for
|L(CR.sub.redw)-L(CR.sub.red{tilde over (x)}).fwdarw.MAX, under the
conditions CR.sub.whitew=CR.sub.white{tilde over (x)},
CR.sub.bluew=CR.sub.blue{tilde over (x)},
CR.sub.greenw=CR.sub.green{tilde over (x)}.
The calculated illumination light spectrum x.sub.red can be
obtained by performing a simulation such that it becomes an
illumination light spectrum that emphasizes only red according to
the above formula (5). For example, a generalized reduced gradient
method (GRG) may be used, the present invention is not limited
thereto and other methods may be used. In addition, conditional
expressions with respect to white, blue and green represented in
the formula (5) may be established in cases in which differences
between the right terms and the left terms are equal to or less
than a certain threshold value as well as cases in which the right
terms are exactly the same as the left terms.
In addition, when an illumination light spectrum can be represented
by a linear sum of N functions (n.sub.k) (for example, when a light
source device that is composed of LEDs of multiple colors and can
control brightness of each LED is used), {tilde over (x)} can be
represented by the following formula (6). [Formula 6] {tilde over
(x)}=.SIGMA..sub.k=1.sup.N.alpha..sub.kn.sub.k, (6)
Accordingly, unknown variables when the calculated illumination
light spectrum x.sub.red is obtained are a number N of
.alpha..sub.k and thus the amount of calculations can be
reduced.
In addition, the illumination light spectrum calculator 121
transmits M data sets composed of the designated conditions and
obtained calculated illumination light spectra, and the reference
illumination light spectrum to the illumination light spectrum
analyzer 122.
The illumination light spectrum analyzer 122 generates element
spectra that satisfy the plurality of designated conditions on the
basis of the calculated illumination light spectra that satisfy the
designated conditions and the reference illumination light spectrum
with respect to the plurality of designated conditions.
Specifically, the illumination light spectrum analyzer 122 analyzes
the calculated illumination light spectra and calculates P element
spectra such as element spectra that "emphasize only blue", element
spectra that "emphasize only green" and element spectra that
"emphasize only red."
For example, in the case of the calculated illumination light
spectrum x.sub.red obtained using the aforementioned formula (5),
an element spectrum e.sub.red that "emphasizes only red" is
calculated using the following formula (7). [Formula 7]
e.sub.red=w-x.sub.red (7)
Meanwhile, the value of each wavelength of an element spectrum may
be a negative value.
Further, as a method of calculating an element spectrum, methods
such as (1) a method of calculating the average of differences
between calculated illumination spectra when the chroma of red is
changed at specific intervals (e.g., increased 10%, increased 20%)
as an element spectrum, (2) a method of calculating an element
spectrum which emphasizes red on the basis of a condition that the
element spectrum which emphasizes red is perpendicular to an
illumination light spectrum (spectrum of white) and spectra of blue
and green of the color chart (the same with respect to green and
blue), and the like can be employed, but the present invention is
not limited thereto.
In addition, the illumination light spectrum analyzer 122 transmits
the P calculated element spectra to the element spectrum storage
123.
The element spectrum storage 123 stores the plurality of element
spectra acquired by the illumination light spectrum analyzer
122.
Specifically, the element spectrum storage 123 stores the P element
spectra. The element spectra may be stored in an external storage
medium.
Then, the element spectrum storage 123 transmits the stored P
element spectra to the weighting processor 300.
The designated condition input unit 200 receives input of
designated conditions and transmits the received designated
conditions to the weighting processor 300.
The weighting processor 300 selects at least one element spectrum
for satisfying the input designated conditions from the plurality
of element spectra and determines a weight for each of the at least
one selected element spectrum.
Specifically, the weighting processor 300 selects at least one
element spectrum for realizing the input designated conditions from
the P element spectra. For example, selection may be performed
using a method of selecting only an element spectrum corresponding
to a specific color when only the specific color is desired to be
emphasized, a method of selecting a plurality of element spectra
corresponding to colors constituting a color that is composed of
two or more colors when the color is desired to be emphasized, and
the like. Meanwhile, an element spectrum for realizing each
designated condition may be determined in advance for each
designated condition.
In addition, the weighting processor 300 determines a weight for
each of the at least one selected element spectrum according to the
designated conditions. For example, when red and blue are desired
to be emphasized, determination is performed using a method of
increasing a weight of an element spectrum for red and a weight of
an element spectrum for blue when red is desired to be more
emphasized and determining a weight of an element spectrum in
accordance with a degree of emphasis of red when only red is
desired to be emphasized, and the like. Meanwhile, a weight of an
element spectrum for realizing each designated condition may be
determined in advance for each designated condition.
Further, the weighting processor 300 transmits the at least one
selected element spectrum and the weight for each of the at least
one selected element spectrum to the composite illumination light
spectrum calculator 500.
The reference illumination light spectrum input unit 400 receives
input of the reference illumination light spectrum serving as a
reference for the illumination control apparatus 10 or stores the
reference illumination light spectrum in advance.
Then, the reference illumination light spectrum input unit 400
transmits the reference illumination light spectrum to the
composite illumination light spectrum calculator 500.
The composite illumination light spectrum calculator 500 calculates
a composite illumination light spectrum that is an illumination
light spectrum satisfying the input designated conditions on the
basis of the plurality of element spectra generated by the element
spectrum calculator 120, the input reference illumination light
spectrum, and the input designated conditions.
Specifically, the composite illumination light spectrum calculator
500 calculates the composite illumination light spectrum obtained
by weighting-adding a plurality of selected element spectra to the
reference illumination light spectrum.
Then, the composite illumination light spectrum calculator 500
transmits the calculated composite illumination spectrum to the
illumination light generator 600.
The illumination light generator 600 generates illumination light
on the basis of the composite illumination light spectrum
calculated by weighting each of the at least one selected element
spectrum and adding or subtracting the at least one weighted
element spectrum to or from the reference illumination light
spectrum and radiates the illumination light to the object through
the output unit 700.
Specifically, the illumination light generator 600 generates
illumination light having the composite illumination light
spectrum. For example, when the output unit 700 is an illumination
device composed of LED light sources having multiple colors,
emission intensity of the LED light source of each color is
determined on the basis of the composite illumination light
spectrum. Meanwhile, a function of controlling emission of each LED
light source on the basis of input/output characteristic data of
each LED light source may be included.
In addition, when an error is received from an accuracy
determination unit 820, the illumination light generator 600
corrects the illumination light to be output on the basis of the
error and the composite illumination light spectrum and radiates
the corrected illumination light through the output unit 700.
The output unit 700 is composed of LED light sources having
multiple colors and turns on the LED light source of each color
according to emission intensity of the LED light source of each
color included in the generated illumination light.
When an error between the composite illumination light spectrum and
a measurement result of the spectrum of the illumination light
radiated to the object is equal to or greater than a predetermined
reference value, the feedback processor 800 transmits the error to
the illumination light generator 600.
Specifically, the feedback processor 800 includes an illumination
light spectrum measurement unit 810 and the accuracy determination
unit 820.
The illumination light spectrum measurement unit 810 measures the
spectrum of the illumination light radiated by the output unit 700
using a spectral radiance meter or the like. Meanwhile, the object
receiving the illumination light radiated through the output unit
700 may be imaged using a camera having three or more color
channels and the spectrum of the illumination light may be
estimated and measured from the image.
Then, the illumination light spectrum measurement unit 810
transmits the measured spectrum of the illumination light to the
accuracy determination unit 820.
The accuracy determination unit 820 compares the composite
illumination light spectrum acquired by the composite illumination
light spectrum calculator 500 with the spectrum of the illumination
light measured by the illumination light spectrum measurement unit
810 and determines whether an error therebetween is equal to or
greater than the predetermined reference value.
When the error is equal to or greater than the reference value, it
is determined that the accuracy of the output illumination light is
not sufficient and the error is transmitted to the illumination
light generator 600.
On the other hand, when the error is less than the predetermined
reference value, the reference illumination light spectrum stored
in the reference illumination light spectrum input unit 400 is
updated to the measurement result of the spectrum of the
illumination light radiated to the object.
<Example of Illumination Control Apparatus According to
Embodiment of the Present Invention>
Next, an example of the illumination control apparatus 10 according
to the present embodiment will be described.
In the present example, it is assumed that the illumination control
apparatus 10 uses a light source device composed of 6 types of LEDs
shown in FIG. 3 as the output unit 700.
First, it is assumed that the spectral reflection factor
acquisition unit 110 acquires a spectral reflection factor of each
color in advance using an existing color chip in the present
example. FIG. 4 shows spectral reflection factors with respect to
blue, green and red acquired from the color chip.
In addition, it is assumed that the reference illumination light
spectrum acquisition unit 140 acquires a reference illumination
light spectrum composed using the illumination control apparatus 10
as shown in FIG. 5 (solar light composed using LEDs of FIG. 5).
The illumination light spectrum calculator 121 obtains calculated
illumination light spectra (specifically, the parameter
.alpha..sub.k in the formula (6)) using GRG. FIG. 6 shows an
example of calculated illumination light spectra that maximize the
chromas of blue, green and red.
In addition, the element spectrum generator 100 generates element
spectra with respect to blue, green and red shown in FIG. 7 on the
basis of the acquired calculated illumination light spectra with
respect to blue, green and red. FIG. 7 shows element spectra
calculated with respect to blue, green and red.
Next, three designated conditions for respectively emphasizing the
chromas of blue, green and red are input to the designated
condition input unit 200.
Further, the same reference illumination light spectrum as that of
the reference illumination light spectrum acquisition unit 140 is
input to the reference illumination light spectrum input unit
400.
Results obtained by plotting color distributions of a composite
illumination light spectrum when the parameter k.sub.i of the
formula (3) has been changed using the acquired element spectra on
the basis of the aforementioned three designated conditions on a
chromaticity diagram CIE-u'v' is shown in FIG. 8.
In all cases, changes in chromas of blue, green and red while the
appearance of white is maintained (metameric white) can be
confirmed.
That is, the results of FIG. 8 show that hue is also changed such
that triangles having three points representing blue, green and red
as vertexes are enlarged, and chroma and hue can be emphasized
while maintaining white balance and overall color balance using the
illumination control apparatus 10 according to the present
embodiment.
<Operation of Illumination Control Apparatus According to
Embodiment of the Present Invention>
FIG. 9 is a flowchart showing an element spectrum generation
processing routine according to an embodiment of the present
invention.
When an element spectrum generation processing command is input to
the illumination control apparatus 10, the element spectrum
generation processing routine shown in FIG. 9 is executed in the
element spectrum generator 100.
First, the characteristic information acquisition unit 130 acquires
statistical information about a target region, a sensitivity
characteristic of an imaging device such as a camera, an
illumination light spectrum during imaging, and a spectral
reflection factor of an object in step S100.
The imaging unit 111 images an image of the object that is a
subject of an observation target or a color chip such as a color
chart used as a reference with a predetermined number (X) of color
channels (bands) using an imaging device (not shown) in step
S110.
The spectral reflection factor calculator 112 calculates a
plurality of spectral reflection factors on the basis of image data
or spectra of the X color channels acquired in step S110 and the
statistical information about the target region, the sensitivity
characteristic of the imaging device, the illumination light
spectrum during imaging, and the spectral reflection factor of the
object acquired in step S100 in step S120.
The spectral reflection factor storage 113 stores L spectral
reflection factors calculated in step S120 in step S130.
The illumination light spectrum calculator 121 acquires the L
spectral reflection factors stored in the spectral reflection
factor storage 113 in step S140.
The illumination light spectrum calculator 121 acquires a reference
illumination light spectrum obtained by the reference illumination
light spectrum acquisition unit 140 in step S150.
The illumination light spectrum calculator 121 acquires M
designated conditions acquired by the designated condition
acquisition unit 150 in step S160.
The illumination light spectrum calculator 121 calculates
calculated illumination light spectra that are illumination light
spectra satisfying a plurality of designated conditions on the
basis of the reference illumination light spectrum and spectral
reflection factors corresponding to the designated conditions with
respect to the plurality of designated conditions in step S170.
The illumination light spectrum analyzer 122 generates element
spectra that satisfy the plurality of designated conditions on the
basis of the calculated illumination light spectrums satisfying the
designated condition and the reference illumination light spectrum
with respect to the plurality of designated conditions in step
S180.
The element spectrum storage 123 stores the plurality of element
spectra acquired in step S180 in step S190.
FIG. 10 is a flowchart showing an illumination control processing
routine according to an embodiment of the present invention.
When designated conditions are input to the designated condition
input unit 200, the illumination control processing routine shown
in FIG. 10 is executed in the illumination control apparatus
10.
First, the weighting processor 300 acquires a plurality of element
spectra stored in the element spectrum storage 123 in step
S200.
The reference illumination light spectrum input unit 400 receives
input of a reference illumination light spectrum serving as a
reference for the illumination control apparatus 10 in step
S210.
The designated condition input unit 200 receives input of
designated conditions in step S220.
The weighting processor 300 selects at least one element spectrum
that satisfies the input designated conditions from the plurality
of element spectra and determines a weight for each of the at least
one selected element spectrum in step S230.
The composite illumination light spectrum calculator 500 calculates
a composite illumination light spectrum that is an illumination
light spectrum satisfying the designated conditions on the basis of
the plurality of element spectra acquired in step S200, the
reference illumination light spectrum received in step S210, and
the designated conditions received in step S220 in step S240.
The illumination light generator 600 radiates illumination light to
an object through the output unit 700 on the basis of a composite
illumination light spectrum calculated by weighting each of the at
least one selected element spectrum and adding or subtracting the
weighted element spectrum to or from the reference illumination
light spectrum in step S250.
The illumination light spectrum measurement unit 810 measures a
spectrum of the illumination light radiated in step S250 using a
spectral radiance meter or the like in step S260.
The accuracy determination unit 820 compares the composite
illumination light spectrum acquired in step S240 with the spectrum
of the illumination light measured in step S260 to calculate an
error therebetween in step S270.
The accuracy determination unit 820 determines whether the error is
equal to or greater than a predetermined reference value in step
S280.
When the error is equal to or greater than the predetermined
reference value (YES in step S280), the accuracy determination unit
820 determines that the accuracy of the output illumination light
is not sufficient and transmits the error to the illumination light
generator 600 in step S290. In step S300, when the error is
received from the accuracy determination unit 820, the illumination
light generator 600 corrects the illumination light on the basis of
the error and the composite illumination light spectrum, radiates
the illumination light through the output unit 700, returns to step
S260 and repeats the processes of steps S260 to S280.
On the other hand, when the error is less than the predetermined
reference value (NO in step S290), the accuracy determination unit
820 updates the reference illumination light spectrum stored in the
reference illumination light spectrum input unit 400 to the
measurement result of the spectrum of the illumination light
radiated to the object in step S310 and proceeds to step S320.
The illumination control apparatus 10 determines whether to end
processing in step S320.
When processing does not end (NO in step S320), the routine returns
to step S220 and repeats steps S220 to S310. When processing ends
(YES in step S320), the processing ends.
As described above, according to the illumination control apparatus
according to an embodiment of the present invention, it is possible
to emphasize the chroma of a specific color with respect to an
object without affecting the color of illumination light by
generating illumination light to be radiated to the object in such
a manner that an element spectrum in accordance with designated
conditions for chroma adjustment from among a plurality of element
spectra that are spectra for being added or subtracted to or from a
reference illumination light spectrum that is an illumination
spectrum serving as a reference and for performing chroma emphasis
of the specific color without affecting the color of the
illumination light is added or subtracted.
In addition, it is possible to obtain a composite illumination
light spectrum through simple calculation because each of the
plurality of element spectra is weighted on the basis of designated
conditions. Further, it is possible to reproduce fine adjustment
and continuous change of the chroma of a color using a weight.
Meanwhile, the present invention is not limited to the
above-described embodiment and may be modified and applied in
various manners without departing from the scope of the
invention.
Although the numbers of spectral reflection factors, designated
conditions and element spectra for representing plural numbers are
respectively indicated by L, M and P in the above-described
embodiment, all of the numbers may be identical.
Furthermore, when the accuracy determination unit 820 updates the
reference illumination light spectrum, the element spectrum
generator 100 may be configured to re-generate element spectra on
the basis of the updated reference illumination light spectrum.
In addition, designated conditions may include characteristics of
illumination used in the illumination light generator 600 (the
spectrum, colorimetric value, brightness, input/output
characteristics, and the like of an LED light source of each color
when the illumination light generator 600 is composed of LED light
sources of multiple colors) in addition to the aforementioned
conditions with respect to colors. In this case, it is possible to
reduce the amount of calculations and calculation time because
combinations of LED light sources are limited.
Moreover, an example in which the element spectrum calculator 120
calculates an element spectrum that satisfies a condition that
"appearance of white" does not change under the reference
illumination light spectrum has been described. However, the
element spectrum calculator 120 may calculate an element spectrum
on the basis of a background part (e.g., an uncolored part (paper
serving as a foundation) or a region in a background color in a
picture) and a part in which appearance color is not desired to
change (e.g., a main color region of a subject or a normal region
at the time of determination of normality and abnormality).
Furthermore, although an embodiment in which a program is installed
in advance has been described in the present specification, the
program may be provided by being stored in a computer-readable
storage medium.
REFERENCE SIGNS LIST
10 Illumination control apparatus 100 Element spectrum generator
110 Spectral reflection factor acquisition unit 111 Imaging unit
112 Spectral reflection factor calculator 113 Spectral reflection
factor storage 120 Element spectrum calculator 121 Illumination
light spectrum calculator 122 Illumination light spectrum analyzer
123 Element spectrum storage 130 Characteristic information
acquisition unit 140 Reference illumination light spectrum
acquisition unit 150 Designated condition acquisition unit 200
Designated condition input unit 300 Weighting processor 300 400
Reference illumination light spectrum input unit 500 Composite
illumination light spectrum calculator 600 Illumination light
generator 700 Output unit 800 Feedback processor 810 Illumination
light spectrum measurement unit 820 Accuracy determination unit
* * * * *